EVALUATION OF THE CORROSION INHIBITION OF STEEL IN ACID MEDIUM USING THE EXTRACT OF Annona Muricata L.

Abstract

In this research the results of the evaluation of corrosion inhibition effect of an ethanolic extract obtained from the fruit peels of Annona muricata L. by means of gravimetric (weight loss) and electrochemical (potentiodynamic polarization) techniques and microscopy SEM are reported. The tests were performed using steel SAE 1008 in acid medium (HCl 0.5M) in absence and presence of the inhibitor. The corrosion inhibitor was tested in five different concentrations of 1-6% v/v. The results indicate that with the increase of the inhibitor extract concentration the corrosion rate of steel decreases and the inhibition efficiency increases reaching values close to 90%. All weight loss and electrochemical results show that their inhibition mechanism is due to the adsorption of inhibitor molecules on the metal, which followed a Langmuir adsorption isotherm. The SEM analysis of the steel samples after their immersion in HCl 0.5M solution in the presence of the inhibitor extract evidenced an improvement in their surface finish compared to the attack in their absence, confirming their ability to inhibit the corrosion of the extract.